Vacuum power clutch mechanism



March 27, 1934. H, J, DE N, MccoLLUM Er L 1,952,767

VACUUM POWER CLUTCH MECHANISM original Filed Feb. 17, 1931 A oRNEYPatented Mar. 27, 1934 TES PATENT OFFICE t pasate: VACUUM rowEa CLUTCHMECnANlsM Henry John De Neville McCollum and James Harry KeighleyMcCollum, Elberon, N. J.

Application February 17, 1931, Serial No. 516,368 Renewed September 26,1933 7 Claims.

Our inventionA relates to improvements in vacuum power clutches and theobjects of our improvements are, first, to provide a mechanism of thesimplest possible construction, second, to provide a mechanism of thegreatest reliability at a minimum cost of construction. Third, toprovide a mechanism with a minimum cost of installation. Fourth, toprovide a mechanism satisfactorily meeting' all the requirements of apower operated clutch. Fifth, to provide a mechanism giving true freewheeling in all gears including reverse. Sixth, to provide a mechanismin which the engine can be used as a brake in all gears includingreverse. Seventh. To provide simple, mechanical and automaticallyoperating lmeans for permitting a rapid initial movement of theclutch-engaging mechanism and compelling a subsequent slower rate ofmovement during the 20 completion of the clutch engagement, this'beingtechnically known as a two-stage mechanism.

By the term free wheeling above used, we

mean a free rolling or coasting movement of the car under the influenceof gravity, or of the cars 25 momentum, without the transmission of suchmotion to the motor, which may be then throttled down to a low speed ofrotation.

We attain these objects by the mechanism illustrated in the accompanyingdrawing in which like numbers represent the same parts throughout and inwhich- Fig. 1 shows a sectional view of the mechanism, Fig. 2 a detailedsectional vew of the clutch, and Figs. 3 and 4 show parts of themechanism in 35 different positions of angularity of the clutch lever.

Throughout the drawing -like reference characvters indicate like parts.Referring to Fig. 1, the parts of a standard form of motor car thereinillustrated comprise the fo1lowing:' the intake o manifold l, to whichthe carburetor 2 is connected, the usual butterfly valve of suchcarbureto being shown at 3, and the throttle lever at 6, the usual stoparms 4 and 5 on the shaft of the valve cooperating with the stop rib 4aon the 4, carburetor and the tension spring 7'normally holding thecarburetor throttle in the position shown for idling the motor. Asection-of the floor board is shown at 27, through which projects theaccelerator operating pedal 26 which, in the arrangement shown, has itsother end pivoted at l26 to the accelerator link 22 and also to thelever 21 which is fulcrumed at 29 to the bracket 28, carried by the footboard. The accelerator 55 link 22 telescopes into the sleeve 24 carriedby the throttle `operating link 23, 'the parts being- `so proportionedthat when the pedal or button carried by is in its position of rest, asshown, and the motor is idling, there will be a gap 25 between the endof link 22 and the bottom of the interior of sleeve 24, thisconstituting a lost motion connection between the accelerator link 22and the throttle.

represents the clutch pedal lever mounted on the clutch operating shaft41 and angularly adjustable with reference thereto by means of thesetscrews 43 and 44. A portion of thechassis or engine subframe isindicated at 38.

A pneumatically operated clutch-controlling mechanism of the classdisclosed in our co-pending applicationV Serial No. 503,767 is alsoshown in Fig. 1, our present invention comprising certain furtherimprovements thereon. This appara-` tus comprises a cylinder 32containing piston 33, having-piston rod 34 and a'hinged mounting on thechassis 36 by means of the pedestal 35, bolted to 36, as indicated at38, 38, to which pedestal lug 42 on the closed end of cylinder 32 ispivoted at 37. The free end of the piston rod 34 has a fork 45 screwedthereon and held in any position of adjustment by lock nut 46. Pivot 47yconnects piston rod 34 to clutch lever 40. There is therefore herecreated a. pneumaticaliy expansible and vcontractile unit hinged to afixed support and to said clutch lever 40, and said unit is connected tothe intake manifold 1 by means of the conduit 39 opening at one end'into the closed end of cylinder 32, and at the other end, through thevalve port 58, into the valve casing 8, which latter is connected byconduit 9 .to the manifold l. In said casing is the plunger valve 10carried by stem 11 projecting through one end of the casing and havingthe locking nuts 17 and 18 on its projecting portion which are in thepath of movement of the free end of lever 21'.y The end of stem l1 isnested in the guide 19 carried by the footboard 27. A spiral compressionspring 16 surrounds valve 8 and is conned between the right hand end ofthe valve casing and the head of the valve. 12 is an axial boreextending through the valve and stem to. a point in the latter exterioroLcasing 8, where there is a port 13 opening to the atmosphere. 14 and15 are locking nuts for controlling the eifective area of opening o1 airinlet v13. The usual pipe connections for Joining conduit 39 (whichwould usually be aA -ilexible copper pipe) tn velve and cylinder `areshown at 59 and 80.

Anair leakage port 61 in conduit 39 has a very small xed cross sectionalarea, and `31 reprelos 'inFg.3.

sents an adjustable air inlet device connected to the interior of saidconduit.

30 is a semicircular spring anchored on bracket 28 and having its freeend engaging a notch in the surface of lever 21 and so stressed as tonormally tend to swing lever 21 in a clockwise direction on its fulcrumor pivot 29 and maintain all parts shown in Fig. 1 in the position thereillustrated, the suction valve 8-10 being then open so that the manifoldsuction has pulled piston 33 to the closed end of cylinder 32, andthereby pulled the clutch lever 40 into the position producing completedisengagement of the clutch.

'I'he preferred proportion of the parts is such as will produce theresults illustrated in Figs. 3 and 4 where the angle between thestraight lines passing through the axis of clutch shaft 41 and throughthe axis of pivot pin 47, and the straight line also passing throughaxis of pin 47 and that of pivot pin 37, equals or slightly exceeds 90degrees when the clutch is in fully engaged position (as indicated inFig. 3) and approximates 180 degrees when the clutch is in fullydisengaged position as indicated in Fig. 4.

As the result of this arrangement, whenever the suction valve 10 isclosed the volume of air that will thereafter flow at a uniform rateinto said cylinder 32 through ports 13 and 61, or through 61 andadjustable valve 31 (or through so many of them as may have been leftopen) will permit piston 33 to travel toward the open end of cylinder 32at a substantially uniform rate of speed under the action of the clutchsprings, and consequently, as a result of the relative angularites oflever 40 and piston rod 34 above described, such uniform movement ofpiston 33 will produce at first a relatively rapid clockwise rotation ofclutch shaft 41 which will gradually decrease in speed as the clutchlever approaches the position of complete clutch engagement shown Thedescribed arrangement of air inlet ports forms a convenient andcontrollable means for applying a substantially constant resistance tomovement of piston rod 34 toward clutch lever 40, not sufficient,however, to overcome the pull of the clutch springs.

Referring to Fig. 2 there is there shown a standard form of clutch whichhas been employed in a widely used make of motor cars, and which isparticularly adapted to cooperate with our above described invention, asthe engaging and 'disengaging movements of the clutch surfaces areextremely small. 5l is the flywheel bolted to a flange 62 on the end ofthe engine crank shaft 64 and carries part of a ball bearing set 57, theother ball race of which is fast on transmission shaft 48, which carriesclutch disc 54, having annular clutch linings 55 and 56. Throwoutbearing 49 transmits pedal pressure to throwout ngers 50, which engagethe heads of bolts 63, 63, set in the annular pressure plate 52, andpull the latter away from clutch lining 55 against the resistance ofsprings 53, 53.

As shown in Fig. 2 the face of clutch disc 54 is at throughout itsentire diameter and the linings 55 and 56 which are fastened to saidclutch disk are made of the least compressible form of clutch liningmaterial such as the moulded type and the clutch actuating mechanism isso designed as to allow complete engagement and disengagement of theclutch with the least possible motion of the clutch pedal. With theparts in the positions shown in Fig. 1 and the motor weaver torsionspring 30, and the consequent pull of lever 21, transmitted through nut17 and valve stem 11, against the action of the compression spring 16.This connects the cylinder 32 with the intake manifold 1 by means of thepassageways 9 and 39 and the vacuum in the cylinder 32 to the left Vofthe pist-on 33 causes the piston 33 to be held in the position shown.The clutch pedal is adjusted by means of the threaded fork 45, pistonrod. 34 and lock nut 46 and the adjust-ments 43 and 44 so that with thepiston in the position shown, the clutch is just completely disengaged.This is the position for free wheeling or coasting, changing gears andidling while in gear with the car at a standstill. To start the car froma standstill the transmission is put in gear and the pedal plunger 20depressed to a point depending upon the speed of starting desired. Therst motion of the accellerator takes up the lost motion of the gap 25and at the Sametime allows valve 10 to seat by the action of the spring16 disconnecting the cylinder from the intake manifold. The air vent 12with the adjustable opening 13 allows air to enter the cylinder 32allowing the clutch to engage with a speed depending upon the adjustmentof the opening 13, the diameter of the cylinder 32, the angularity ofthe clutch pedal arm and the pressure of the clutch springs. Thenecessity of adjusting the mechanism so that the clutch is just fullydisengaged when thel piston is against the bottom of the cylinder asshown in Fig. 1 is due to the fact that it is necessary to have theclutch start to engage a very short time after the plunger has beendepressed. This allows any desired amount of clutch slipping for properstarting and accellerating at any speed in any gear including reverse.The fact that full en-l gagement and disengagement of the clutch isobtained with a minimum of movement of the 115 clutch pedal and piston33 allows a minimum opening of the air vent 13 with consequent slowengagement of the clutch makes possible maximum smoothness of startingand all other conditions of operation. This minimum movement 120 of theclutch pedal and piston 33 also provides for maximum rapidity of clutchdisengagement, preventing the car from running up on the engine when theaccellerator is released with the car in motion and in gea'r. Theadjustable air vent 31 can be used in place of the air vent shown at 12and 13 Fig. 1 if desired. The object of the lost motion gap in thethrottle rod -Y 22, 23, and 24 is to allow the engagement of the clutchwhile the throttle is in the idling position and the motor idling, forthe purpose of idling along with the car and for using the engine as abrake in any gear including reverse. While the use of this mechanismwith a flat clutch plate is preferred, it can be used in connection withthe spring type or crimped type of clutch plat?` by taking advantage ofthe angularity of the clutch pedal arm and piston rod as shown in Figs.3 and 4 which show the clutch pedal in the fully engaged and disengagedpositions respectively.y It will be seen by referring to Fig. 4 that avery small motion of the piston will give a comparatively large motionto the clutch pedal arm allowing a more rapid iirst motion of same tocompensate for the larger motion of the clutch 145 pedal arm when usingthe spring or crimped type of clutch plate or in the multiple disk type.

This rapid first motion of the clutch pedal arm allows the clutch tomove rapidly up to a. partially engaged position and to more slowly com-150 plete the engagement, permitting of a smooth start withoutunnecessary slipping of the clutch. Although the poppet valve is thepreferred form due to the fact that it requires no lubrication, issimpler of construction and more reliable, is practically free from wearand gives the most perfect seal, yet any other suitable'form of valvecan be used, and even if the poppet form of valve be retained, it is notnecessary that the air inlet passageway shown in the drawing as'consisting of the axial bore 12 should remain in that particularlocation, since it might be moved to either side of the valve axis.

The type of flat-disk, short-coupled clutch shown in Fig. 2 isespecially adapted for use in the particular arrangement of pneumaticpower units herein shown and above described. .The engaging anddisengaging movements of pressure ring 52 are very slight, and theresistance of springs 53, 53, to disengaging movement thereof isconsiderable, but the multiplied leverages produced by clutch flngers50,50, and by clutch lever 40 overcome that resistance under the pull ofpiston 33, which is preferably of a diameter larger than is usual inapparatus 'of ythis type. The piston stroke, however, can be madeshorter -than is usual, because of the short travel of the clutch ring52, andconsequently the volumetric displacement of the piston is ofabout the'standard amount and the intake manifold suction will thereforepull itback through the full stroke as quickly as in other arrangements,and so clutch disengagement will not be unduly delayed.

When the operation is reversed and air is admitted to cylinder 32 topermit engagement of the clutch a slight initial movement of piston 33to the right, looking at Fig. 4, permits a con-- siderable angle ofclockwise' swinging of clutch lever 40, because of the nearly fiatcondition of the toggle joint 41, 40, 47, 34, 42v and 37 then obtaining.Consequently clutch ring 52 then quickly moves to the left (Fig. 2) and,squeezes the parts 55, 54, 56 (the clutch elements carried by thetransmission shaft 48) against the interior face of the fiy wheel 51(which is rotated by the motor).

Thereafter the further movement of clutch ring 52 is slight'and slowbecause the suction drag of piston 33 on the rising clutch lever 40increases rapidly in effect with every degree of the latters swingingmotion to the right and upward, as indicated in Fig. 3. This finalmotion, however, merely creates slowly increased compression of clutchlinings 55 and 56 and the consequent increase of clutch friction orgripping action.

The disengaging action of the clutch is so quick and the clutch engagingaction so rapid and smooth in character that the lost motion mechanism23-24 in the throttle connection can sometimes be dispensed withentirely.

Various changes could be made in the details of construction hereinshown and described as affording the preferred embodiment of ourinvention, without departing from the underlying novel principles ofconstruction of the same as above explained. Thus, other forms ofapparatus constituting a pneumatically expansible and contractilepower-operated unit might be substituted for the cylinder and `pistonshown, and other means for guiding the power-driven end of piston rod 34along a substantially straight line might be used in place of therigidconnection of said piston rod to a piston sliding in a cylinder whichswings about a fixed pivot, as here illustrated. Such changes of form`but not of substance, so far as `the mode of operation and resultsobtained are concerned would still leave such modified constructionwithin the definition of the appended claims.

Having now'fully described our invention, what we claim is: Y

1. In a pneumatic power-developing attachment for operating motor carclutches the combination, with a clutch actuating lever and spring meansnormally tending to close the clutch, of -a pneumatically expansible and'contractile unit hinged at one extremity to a fixed support and to saidlever at the other, the parts being so proportioned that the anglebetween the straight line connecting the axes of said hinges and thestraight line which passes through the fulcrum of said lever and throughthe axis of the hinge connecting it to said unit approximates 90 degreeswhen the clutch is in closed position, and approximates 180 degrees whenthe clutch lever is at the limit of its clutch opening movement. 2. Anapparatus such as defined in claim 1 combined with means for permittinga substantially uniform rate of flow of air into said unit during theclutch closing movement of said lever.

3. An apparatus such as dened in claim 1 combined with a clutch assemblycomprising a fiat pressure ring adapted to be moved by said lever andhaving a minimum limit of clearance movement after disengagement fromits cooperating friction element; whereby in the clutch engagingoperation, a prompt initiation of vcontact between the clutch element isassured, followed by a retarded gradual increase of pressure andconsequent friction between the said elements.

4. In a pneumatic clutch-operating apparatus for motor cars comprising avacuum operable unit operatively connected to a clutch-actuating member,and a conduit connecting said unit with the intake manifold of the motorcar, the combination, with said above described apparatus, of

. a valve for controlling passage of afluid through said conduitcomprising a casing having one port connected to said manifold and asecond port connected to said unit and a valve plunger adapted to openand close said last mentioned port and having a stem which extendsthrough said casing` wall, said valve and stem having an axially locatedbore extending from said valve face to a point in said stem exterior ofsaid casing and having at that point an opening to the atmosphere;whereby, when said valve is seated communication from said unit to saidmanifold will be closed but communication from said unit to theatmosphere will be maintained through said valve bore.

5. In a pneumatic power-developing attachment for operating vmotor-carclutches the combination with a clutch actuating lever which extends inan approximately horizontal direction when at thel limit of its clutchopening movement and swings upward to approximately a vertical positionwhen completing the clutch closing movement, and spring means normallytending to move said lever in a clutch closing direction, of a pneumaticexpansible vand contractile unit hinged to a fixed support at one ofitsextremities and to said lever at the other, the parts being soproportioned that the angle between ninety degrees when the clutch is inclutch closing position and one hundred eighty degrees when the saidclutch lever is at the limit of its clutch opening movement.

6. In a pneumatic power-developing attachment for operating motor-carclutches the combination with a clutch-actuating lever which extends inan approximately horizontal direction when at the limit of its clutchopening movement and swings upward to approximately a vertical positionwhen completing the clutch closing movement, and` spring means normallytending to move said lever in a clutch closing direction, of apneumatically expansible and contractile unit hinged to a xed support atone of its extremities and to said lever at the other, the parts beingso proportioned that the angle between straight lines connecting theaxes of said hinges and the straight line which passes through thefulcrum of said lever and through the axis of the hinge connecting it tosaid unit approximates ninety degrees when the clutch is in closedposition and approximates one hundred and eighty degrees when the saidclutch lever is at the limit of its clutch opening movement.

7. In a pneumatic clutch-operating apparatus for motor cars comprising avacuum-operable unit operatively connected to a clutch-actuating member,and a conduit connecting said unit with the intake manifold of the motorcar, the cornbination, with said above described apparatus, of a valvefor controlling passage of a uid through said conduit comprising acasing having one port connected to said manifold and a second portconnected to said unit and a valve body sliding in said casing andadapted to open and close communication between said unit and manifoldand having a portion extending through said vcasing wall, in which saidvalve body there is a

